The present invention relates to technique of measuring a quantity of air inducted into a cylinder section of an engine in accordance with a quantity of air inside an intake manifold determined by a balance calculation between an inflowing air quantity and an outflowing air quantity. In particular, the present invention relates to such engine cylinder induction air quantity measurement adapted to improve the accuracy of the air quantity measurement.
United States Patent U.S. Pat. No. 6,328,007 B1 (corresponding to Published Japanese Patent application Kokai No. 2001-50091) shows a process of balance calculation between the inflowing and outflowing air quantities to determine an intake manifold inside air quantity, and to calculate an engine cylinder induction air quantity in accordance with the manifold inside air quantity and a cylinder volume. The thus-calculated engine cylinder induction air quantity is used to calculate a fuel injection quantity to achieve a desired air fuel ratio.